My variegated ficus now has some green branches. The branches have both green & variegated leaves on the same branch. Some branches have shoots of each color leaves. Other branches are all green or all variegated. How is this happening. I noticed this change about 4 years ago. It's slow, but interesting.
This is known as "reversion". It is a similar idea to a "plant sport" but is the other way around. Many variegated plants are selected from naturally occurring mutations that grew on a plant with green leaves. In your plant, some of the branches seem to be returning to their original genetic state and producing more green leaves.
This article explains it: